package com.hnevc.xiewenguang;

public class Example01 {
    public static void main(String[] args) {
        double a = 1, b = 2;
        double sum = 0;

        for(int num = 0; num < 20; num++) {
            sum += (double)b / a;
            b = a + b;
            a = b - a;
        }
        System.out.println(sum);
    }
}
